The vicar of Christ Church Eaton, in Norwich, The Rev Dr Patrick Richmond, sparked a debate when he told the General Synod that the Church of England was on course to die out within two decades. Here he sets out why he is so worried.

'I'm completely of the same opinion as he is. I entirely agree with the sentiments and I wish all of us would have a sense of real crisis about this.'

These are the words of the first church estates commissioner, Andreas Whittam Smith, responding to my widely reported question at the General Synod of the Church of England about the possible extinction of the Church. He is responsible for the billions of pounds of Church of England property and assets. His views about finance and risk management should carry some weight.

Contrary to some sensationalising reports, neither of us was saying that the church must fail by 2030, merely that there are real risks converging on the horizon and no room for short-sighted self-congratulation.

Little I am saying is new, but from my experience in Leicester, Cambridge, Norwich and at General Synod we need to raise awareness of reality and risk and of the need to make hard choices more urgently than the Church of England has in the past.

Now is not the time for denial, complacency or procrastination. We need to do research and make realistic projections about future numbers now, given the time it takes for a hugely complex, ancient and traditional organisation like the Church of England to change. A week is long time in politics. I don't want 20 years to be a lifetime for the church. Indeed, I ought to declare an interest; I am 42 so my retirement age takes me far into the projected crises.

In my experience we sometimes shelter behind the questionable assumptions of the projections rather than seeking better projections and planning to avoid risks.

The facts are sobering. In the past 40 years we have lost half of our adult churchgoers and 80pc of our children.

In 2007 good evidence was published that the average age of churchgoers was rising. In 1977 the age profile reflected the general population, but by 2007 churches had twice their fair share of people over the age of 65, and the situation was significantly worse for small churches.

Older people can increase their interest in religion but increasingly people report being 'spiritual' rather than conventionally religious. They cannot come back to church because they were never there in the first place. We need more real research if we are to have a realistic view of how important such factors are.

Furthermore, the number of paid, full time clergy is set to fall as retirements greatly exceed those entering the ministry. The countryside is increasingly serviced by unpaid, self-supporting ministers and volunteers. The signs are these too are disproportionately older than the general population.

The Church has probably never needed as many buildings as we now have (16000 of them, with 12000 historic, listed ones). As I know from personal experience, they take a huge amount of time, money and effort to maintain, let alone improve, and it is often difficult to provide an alternative use for them.

The government has been generous in helping us conserve disused churches but has signalled its wish to withdraw funding in the future. The cost will fall on already hard-pressed church funds. Industrial fund-raising is required and the lottery is hardly the answer. Many are already questioning the role of the Church of England in the state and religion is increasingly less important for most of the young.

Many are already sacrificing themselves for the buildings, but are so many buildings really a Christian priority, with so much poverty and suffering in the wider world? How closely related is the care of buildings to the work Christ calls Christians to do? Perhaps some buildings are central, but all of them? Is it really realistic to expect the non-churchgoing public to help us maintain all our buildings?

While I sympathise with the Rev Peter Mullen in the Daily Telegraph, and totally agree that news of the Church's death has frequently been exaggerated, the Church of England does not believe that when Christ promised that the gates of hell would not prevail against the Church, he meant the specific institution of the Church of England. We need both to look at the reality and do real research if we are to face the future with more than wishful thinking and unfounded optimism.

Some fear running down the church by bad publicity. I sympathise with this fear, but many urge me on. Bad publicity is not our most pressing problem. Many already have the impression that the church is composed of tiny, ageing congregations endlessly fundraising for freezing buildings. We need to deal, not in spin or advertising, but in substance and reality. At least that way we are seen to be realistic and honest.

The prophet Jeremiah had to speak out against those who cried peace when there was no peace, and put their trust in the stones of the Temple, soon to be destroyed. The reality is that some churches are indeed struggling with resources spread ever thinner, while others, doing better, are expected to pay so much to support widespread ministry that they cannot afford to provide the standards most people expect of community services and buildings.

What are we to do? We need long term planning and projections for the future, not just the one, three and five year terms so common, exploring the risks of various scenarios and quantifying them where possible. I and others hope the Church of England's Statistics department will produce better estimates of future numbers of congregations and money so we can judge how we are doing and make realistic plans for a number of scenarios.

Thankfully, much thought is indeed already being given to buildings and mission. General Synod has just backed strategy for mission, but I've frequently encountered one-size fits all approaches in conflict with one another, for example, 'We need to put resources where there is greatest need and opportunity' versus 'we won't close any buildings'; 'Mission doesn't start with buildings, no mission support for buildings' versus 'our buildings are our mission'; 'We are an ageing community' versus 'we will recruit lots of young vicars and youth and children's workers'; 'we need to provide better wedding and funeral ministry and be more efficient' versus 'administration isn't mission.' Instead, we need to be realistic, identifying what works, where, and then be prepared to be radical, to protect it from projected crises.